34. Find First and Last Position of Element in Sorted Array (Leetcode || Medium || Java)

Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value.

If target is not found in the array, return [-1, -1].

You must write an algorithm with O(log n) runtime complexity.

Example 1:

Input: nums = [5,7,7,8,8,10], target = 8
Output: [3,4]

Example 2:

Input: nums = [5,7,7,8,8,10], target = 6
Output: [-1,-1]

Example 3:

Input: nums = [], target = 0
Output: [-1,-1]

Constraints:

• 0 <= nums.length <= 105
• -109 <= nums[i] <= 109
• nums is a non-decreasing array.
• -109 <= target <= 109

SOLUTION:

class Solution {
public int[] searchRange(int[] nums, int target) {
int[] ans = {-1,-1};//declaring array to return

int i = 0;

while(i < nums.length){
if(nums[i] == target){//This loop will give us the first position of target
ans[0] = i;
break;
}

i++;
}

while(i < nums.length){
if(nums[i] == target){//This will give the last position of target
ans[1] = i;
}
i++;
}

return ans;

}
}